1. Field of the Invention
The present invention relates to a ram intake unit employed in a front portion of a motorcycle.
2. Description of the Related Art
In a motorcycle of a kind equipped with a so-called ram induction system, in which an air intake opening for introducing towards a combustion engine an air eventually forming an air-fuel mixture with a fuel, is mounted in a front region of a motorcycle frame structure, an external air is supplied through the air intake opening at the front portion of the motorcycle frame structure to the combustion engine by way of a ram air intake duct and an air cleaner during the travel of the motorcycle. In some of the motorcycles now in use, an acoustic material or a sound absorbing material is applied to inside of the ram air intake duct by means of an adhesive agent such as, for example, one or more lengths of double-sided adhesive tape in order to suppress induction noises then generated in the air intake system.
It has, however, been found that the use of the only adhesive agent to secure the acoustic material often results in removal of the acoustic material from the ram air intake duct by the effect of the incoming wind, which blows during the travel of the motorcycle relatively in a direction opposite to the direction of travel of the motorcycle.